Those scenarios, reports The New York Times, include hypothetical scenarios for the deaths of either Russian President Vladimir Putin, Ukraine's Volodymyr Zelensky, as well as "the removal of leadership within the Russian Armed Forces and a Ukrainian strike on the Kremlin."
It is unclear what the US intends to do in the event that Putin is killed, though they are substantially concerned about a Ukrainian strike on the Kremlin. The Pentagon believes could lead to an escalation of the war, full-scale mobilization, and potential use of nuclear weapons by Putin. Fears of a strike on the Kremlin could be part of the Biden administration's rationale for not sending long-range missiles to Kyiv.
The leaked document also suggested that the war will not end any time soon, but will likely drag on for some time. Each scenario detailed by Pentagon in the leaked document describes how each potentiality "could potentially result in an escalation in Ukraine, a negotiated end to the conflict or have no substantive effect on the war’s trajectory."
Documents were leaked from the Pentagon allegedly by a YouTuber who claimed to have leaked the documents on his discord channel.
This document, titled RELIDO, is dated February 24, and was likely written a year after Russia invaded Ukraine in 2022. US officials neither denied nor confirmed the document's authenticity, but the Times reports that it is similar to other leaked documents.